Well-known local Republican politician Mark Assini appears to be girding for a run against U.S. Rep. Louise M. Slaughter and will make his intentions public on Thursday.

Slaughter, a Democrat from Fairport, was first elected to represent the Rochester area in Congress in 1986, and since then has won re-election against 13 different Republican opponents.

Assini, the 54-year-old Gates town supervisor, apparently would like to be re-election opponent No. 14.

The website “MarkAssiniforCongress.com” was registered last week, and a gun-rights group has posted an online notice stating Assini will announce his congressional bid Thursday evening at the Italian-American Community Center, off Manitou Road in Gates.

Asked Tuesday morning about his possible candidacy, Assisi was coy but only a little.

“On Thursday at 5:30 at the IACC, I’ll be making an announcement relative to my decision about running for the 25th Congressional District seat,” Assini said.

He declined to preview his decision.

It was not clear whether any other Republicans would seek the right to run against Slaughter. Monroe County Republican chairman William Reilich did not return a call for comment Tuesday morning.

The 25th Congressional District comprises all of Monroe County except for the towns of Hamlin, Wheatland, Rush and Mendon.

Assini has been Gates supervisor since 2010. He was a Monroe County legislator from Gates from 1993 to 2005.

Assini has spoken publicly several times about running for Congress, and sought the Republican nomination for the 29th Congressional District in 2004 after that seat was vacated by the retirement of Amory Houghton of Corning. At the time that district included part of Monroe County but was centered on the Southern Tier.

Assisi lost the Republican primary to then-state Sen. John “Randy” Kuhl of Hammondsport, Steuben County, who went on to win the November congressional election.

Slaughter, 84, has stated publicly several times that she is seeking re-election this fall to what would be her 15th two-year term. She is the ranking Democrat, and former chairwoman, of the House Rules Committee.

After eking out a narrow win in 1986 against then-U.S. Rep. Fred J. Eckert, R-Greece, she’s had a relatively easy time at the polls, averaging a margin of 26 points over her Republican opponents.

In 2012, Slaughter beat Monroe County Executive Maggie Brooks, probably the most high-profile opponent she’s faced, with 57 percent of the vote to 42.5 percent for Brooks.